PBR Support for Multiple Tracking Options

The PBR Support for Multiple Tracking Options feature extends the capabilities of object tracking using Cisco Discovery Protocol (CDP) to allow the policy-based routing (PBR) process to verify object availability by using additional methods. The verification method can be an Internet Control Message Protocol (ICMP) ping, a User Datagram Protocol (UDP) ping, or an HTTP GET request.

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Information About PBR Support for Multiple Tracking Options

Object Tracking

Object tracking is an independent process that monitors objects such as the following:

State of the line protocol of an interface

Existence of an entry in the routing table

Results of a Service Assurance Agent (SAA) operation, such as a ping

Clients such as Hot Standby Router Protocol (HSRP), Virtual Router Redundancy Protocol (VRRP), Gateway Load Balancing Protocol (GLBP), and (with this feature) PBR can register their interest in specific, tracked objects and then take action when the state of the objects changes.

PBR Support for Multiple Tracking Options Feature Design

The PBR Support for Multiple Tracking Options feature gives PBR access to all the objects that are available through the tracking process. The tracking process provides the ability to track individual objects--such as ICMP ping reachability, routing adjacency, an application running on a remote device, a route in the Routing Information Base (RIB)--or to track the state of an interface line protocol.

Object tracking functions in the following manner. PBR will inform the tracking process that a certain object should be tracked. The tracking process will in turn notify PBR when the state of that object changes.

How to Configure PBR Support for Multiple Tracking Options

The tasks in this section are divided according to the Cisco IOS release that you are running because Cisco IOS Release 12.3(14)T introduced new syntax for IP Service Level Agreements (SLAs). To use this feature, you must be running Cisco IOS Release 12.3(4)T, 12.2(25)S, or a later release. This section contains the following tasks:

Configuration Examples for PBR Support for Multiple Tracking Options

Cisco IOS Release 12.3(11)T 12.2(25)S and Earlier

In the following example, object tracking is configured for PBR on
routers that are running Cisco IOS Release 12.3(11)T, 12.2(25)S, or earlier
releases.

The configured policy is that packets received on Ethernet interface
0, should be forwarded to 10.1.1.1 only if that device is reachable (responding
to pings). If 10.1.1.1 is not up, then the packets should be forwarded to
10.2.2.2. If 10.2.2.2 is also not reachable, then the policy routing fails and
the packets are routed according to the routing table.

Two Response Time Reporters (RTRs) are configured to ping the remote
devices. The RTRs are then tracked. Policy routing will monitor the state of
the tracked RTRs and make forwarding decisions based on their state.

Example: Configuring PBR
Support for Multiple Tracking Options

The following
example shows how to configure PBR support for multiple tracking options.

The configured
policy is that packets received on Ethernet interface 0, should be forwarded to
10.1.1.1 only if that device is reachable (responding to pings). If 10.1.1.1 is
not up, then the packets should be forwarded to 10.2.2.2. If 10.2.2.2 is also
not reachable, then the policy routing fails and the packets are routed
according to the routing table.

Two RTRs are
configured to ping the remote devices. The RTRs are then tracked. Policy
routing will monitor the state of the tracked RTRs and make forwarding
decisions based on their state.

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Feature Information for PBR
Support for Multiple Tracking Options

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

The PBR
Support for Multiple Tracking Options feature extends the capabilities of
object tracking using Cisco Discovery Protocol (CDP) to allow the policy-based
routing (PBR) process to verify object availability by using additional
methods. The verification method can be an Internet Control Message Protocol
(ICMP) ping, a User Datagram Protocol (UDP) ping, or an HTTP GET request.

The
following commands were introduced or modified by this feature:
setipnext-hopverify-availability.